Lesson 5: Formation of a

V-Shaped Valley

What you should know by the end of this lesson:

Explain the formation of a V-Shape valley

Background

A typical river formation question would be:

Explain the formation of a *.

You may wish to use an annotated diagram in your answer (8)

*The features you can be asked are:

- Waterfalls
- V-shaped valleys
- Meanders
- Ox-Bow Lake

V-Shaped Valleys & Waterfalls usually form in the upper course of rivers, where the land has a very steep gradient.

They are the result of both river erosion and weathering (breaking down of rocks by the weather).

Digital Workbook and Paper Jotter

Draw the annotated diagram for the feature
Write out the explanation under each

Reminder

Fully explained processes will gain you double marks. 1 mark for naming the process and 1 for explaining the term but you NEED to do both to get both marks.

River Landforms: v-Shape Valleys

1. Rivers in the upper course have low discharge but high energy because the valley is steep. This causes vertical erosion to dominate. (1)

2. The river cuts a deep notch down into the landscape using Hydraulic action (1), where water pushes air into cracks, compressing it and weakening the rock (1), and Abrasion (1) which is when material carried in the river erodes the banks by hitting into them (1).

3. As vertical erosion occurs, the valley sides are exposed to freeze-thaw weathering (1), water getting into cracks that freezes and expands (1). This loosens the rocks which fall into the river. (1)

4. As the rocks fall, the valley sides become steeper (1). The rocks which fall into the river assists in the process of abrasion and leads to further erosion (1).

5. The river transports the rocks downstream, the channel is widened and deepened creating a V-shaped valley (1). Many v-shaped valleys forming in a landscape will create interlocking spurs as the river winds between them.

Extra: Interlocking Spurs

In the upper course, there is more vertical erosion. The river cuts down into the valley. If there are areas of hard rock which are harder to erode, the river will bend around it. This creates interlocking spurs of land which link together like the teeth of a zip.